1. Field of the Invention
This invention relates to an electrostatic recording apparatus in which a toner image formed on a photosensitive drum by a developing device is removed by a cleaning device after the toner image is transferred to recording paper.
2. Description of the Prior Art
A cleaning device in an electrostatic recording apparatus is adapted to scrape off by a blade the residual toner from the surface of a photosensitive drum after an electrostatic latent image formed on the drum is developed to a toner image by a developing device and transferred as a visible image onto recording paper, and introduce the scraped toner into a toner recovery vessel by a toner guide member positioned below the blade.
A container body in the cleaning device is disposed so as to face the circumferential surface of the photosensitive drum with a slight clearance kept, of course, between the container body and the surface of the drum, which is a rotary body.
The blade and toner guide member held in the container body are fixed so that they are also spaced slightly from the inner side surface of the container body for the purpose of keeping the blade and toner guide member in close contact with the drum surface and permitting the drum surface to slide on the contact portions of these parts smoothly at all times.
Therefore, especially, in the position close to the inner side surface of the container body, a part of the toner scraped off by the blade or a part of the toner being sent to the toner recovery vessel by the toner guide member scatters and flows out from the clearance between the container body and the drum surface to soil the recording paper and the machine parts.
To solve this problem, Japanese Patent Laid-Open No. 59-34580 and Japanese Utility Model Laid-Open No. 59-151266 propose the provision of a seal member consisting of a resilient material in a predetermined portion of this kind of apparatus. However, such a seal member must be fixed in a predetermined position with a high accuracy, or it constitutes a large load with respect to the rotation of the drum and the movement of the blade. Consequently, this seal member lacks practicality.
Specifically, in the Japanese Patent Laid-Open No. 59-34580, a seal member 21 is arranged on the back side of a sheet-like guide member 22 and fixed to an end seal member 23, as shown in FIG. 4. In such construction, if the seal member 21 is not arranged with a high accuracy, the seal member 21 affects a cleaning blade 24 and the guide member 22 so that the cleaning of the residual toner becomes insufficient and toner is scattered to the outside of the container body.
Further, a portion of the seal member 21 which is fixed to the end seal member 23 shown in FIG. 5A is liable to be separated from the end seal member 23, as shown in FIG. 5B, thereby causing toner to be leaked.
In the Japanese Utility Model Laid-Open No. 59-151266, a seal member 21 is provided along the end portion of the photosensitive drum 25, as shown in FIG. 6.
In such construction, if the seal member 21 is not fixed to an end seal member 23 with a high accuracy, for example, if the seal member 21 is separated from the end portion of the photosensitive member 25 as shown in FIG. 7A, toner will be leaked from the clearance between the two. Alternatively, if the seal member 21 is in contact with the end portion of the photosensitive member 25 under a high pressure as shown in FIG. 7B, a large load will be applied to the photosensitive member 25, or under a low pressure as shown in FIG. 7C, toner will be leaked in the transverse direction between the seal member 21 and the photosensitive member 25.